1. Field of Invention
The present invention relates to an overheating protector for electronic heaters.
2. Related Art
It has been a common means to make use of electronic heat filaments or electronic heat tubes in electronic heaters to generate heat for all sorts of machining or getting warmth for a long time. Since these devices generate a lot of heat, they should have a good control of the high temperature due to the heat in order to prevent such events as human scalding, device burning, or serious fire from happening.
The heaters that have the closest relation to people are home baseboard heaters. Therefore, if the heaters are overheated, there would be direct injury to people in contact or cause safety problem to the space people are occupying. Although usually electronic heaters are provided therein overheating protectors, the ones in conventional electronic heaters are not ideal because conventional baseboard heaters have a larger wind outlet, which is quite different from a usual fan heater that has a smaller wind outlet and lower heat radiation. The area is so large that a thermostat can not effectively detect the temperature in each area of the heater. For example, if the thermostat is mounted in the center, then abnormal operations on both the left and right sides often can not be detected. Thus, the thermostat can not provide perfect protection and all baseboard heater manufacturers do not use them as the overheating protector but use the capillary liner limit control adopted in large air conditioners. This device is an overheating protector that has a thin capillary of about 2 meters long wrapping around the wind outlet of the heater. The thin capillary functions as the overheat detector on each part of the heater. When a local area is overheated, there would be an air pressure change to push a metal chip and timely shut off the power. Since the device utilizes a long and vacuum thin copper tube as a temperature detector that has to be nicely installed at the right position, so there come the following important problems which are not easy to resolve:
1. The installation of the thin copper tube is very troublesome and needs much care. Since the copper tube is thin and long, a deviation of the installation position often results in improper action. If the copper tube is carelessly broken and air leaks in, the whole protector completely loses its function. PA1 2. Moreover, since the inside of the thin and long copper tube has to be vacuum, the manufacture of the protector becomes very difficult. It has to be calibrated to correct temperature settings before use. So usual capillary liner limit controls have a larger precision range (i.e. less precise). The difficulty in manufacture also makes the cost of the protector and thus that of the heater higher. PA1 3. Furthermore, difficult manufacture of protectors also elongates delivery schedule and increases stocking cost. This problem results in frozen capital. Since the capillary is fragile, operational difficulty is another reason for a higher cost.
To solve the above problems, the inventor of the present invention, after long time of thought, experiments and corrections, finally came up with a method for disposing a plurality of thermostats in series at proper positions. This method once and for all solves such problems of installation, precision, fragility, expensive cost and long delivery schedule that are disadvantageous to the manufacture of capillary liner limit controls.